OPERATING THE PULSED DISCHARGED DETECTOR IN BOTH THE ELECTRON-CAPTUREAND PHOTOIONIZATION MODES WITHIN THE SAME GC ANALYSIS

Since the electron-capture detector (ECD) is highly selective, it is i mperative to use a more universal ionization detector in conjunction w ith the ECD in order to detect non-capturing or weakly capturing compo unds. Also in an EC study of weakly or moderately strong electron-capt uring compounds, it is necessary to identify the EC peak of the compou nd by identifying the major component with an ionization detector. In this paper we have shown that the pulsed discharge detector can be int erchanged between the EC and the helium ionization modes within 4-6 s. The application of this procedure has been illustrated with a mixture of alkane/alkene chlorocompounds. The interchange between EC and argo n photoionization modes has also been investigated. The change from EC to argon photoionization also occurs in 4-6 s but the reverse process requires similar to 9 s.